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  • Author or Editor: Tian Chen x
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High- and low-affinity transport systems are the main pathways for the transportation of NO3 and NH4 + across intracellular membranes. NO3 and NH4 + are assimilated through different metabolic pathways in plants. Fifteen ATP molecules are hydrolyzed in the metabolic process of NO3 ; however, only five ATP molecules are hydrolyzed in that of NH4 +. In this research, seedlings of Iris pseudacorus and Iris japonica were used as the experimental materials in the NO3 :NH4 + = 30:0, NO3 :NH4 + = 28:2, NO3 :NH4 + = 27:3, NO3 :NH4 + = 15:15, NO3 :NH4 + = 3:27, and NO3 :NH4 + = 0:30 treatments at the 7.5 mmol·L−1 the total nitrogen content (TN). The intracellular free energy was represented by physiological resistance (R) and physiological impedance (Z) according to the Nernst equation and could conveniently and comprehensively determine the cellular metabolic energy (GB). The maximum absorption rate (Vmax) and Michaelis constant (Km) for NH4 + and NO3 uptake were calculated according to the kinetic equation. The results showed that the cellular metabolic energy (GB) of I. pseudacorus was 1 to 1.5 times lower than that of I. japonica at each treatment on the 10th day. The GB values of I. pseudacorus and I. japonica seedlings increased with increasing NH4 + concentration. However, there was a turning point at the NO3 :NH4 + = 15:15 treatment for the cellular metabolic energy of I. pseudacorus and I. japonica. Correlation analysis showed that the value of cellular metabolic energy was negatively correlated with the Vmax and Km for NO3 uptake, whereas it was positively correlated with that for NH4 + uptake. These results demonstrate that the NO3 :NH4 + = 27:3 treatment level was the most suitable for I. pseudacorus and I. japonica. This indicates that the greater cellular metabolic energy is the most suitable for plant growth when the concentration of ammonium or nitrate had no significant difference at treatment. These results provide a simple and rapid solution for removal of nitrogen by determination of cellular metabolic energy.

Open Access

Insect traps are vital component of many entomological programs for detection and monitoring of insect populations. We equipped yellow (YC), blue (BC) sticky card (BC) with 530 nm lime green (LED-YC) and 470 nm blue (LED-BC) light-emitting diodes, respectively that increased trap catches of several insect pests. The LED-YC traps caught 1.3, 1.4, 1.8, and 4.8 times more adult greenhouse whitefly Trialeurodes vaporariorum (Westwood), sweetpotato whitefly Bemisia tabaci (Gennadius) biotype B, cotton aphids Gossypium hirsutum (L.), and fungus gnats Bradysia coprophila (Lintner), respectively, compared with standard YC traps. The LED-YC traps did not catch more Eretmocerus spp. than the standard YC traps. Eretmocerus spp. are important B. tabaci parasitoids used in greenhouse biological control programs. For whitefly control in greenhouse the 530 nm lime green LED equipped plastic cup trap designed by Chu et al. (2003) is the better choice than LED-YC trap because it catches few Eretmocerus spp. and Encarsia spp. whitefly parasitoids released for B. tabaci nymph control. The LED-BC traps caught 2.0-2.5 times more adult western flower thrips Franklinella occidentalis (Pergande) compared with the standard BC traps.

Free access

Insects in a commercial poinsettia (Euphorbia pulcherrima) greenhouse were monitored with yellow sticky card (YC) traps and YC equipped with 530-nm lime green light-emitting diodes (LED-YC) traps from 3 June to 25 Nov. 2002. Pest insects were: dark-winged fungus gnat (Bradysia coprophila), sweet potato whitefly (Bemisia tabaci) biotype B (= B. argentifolii), western flower thrips (Frankliniella occidentalis) and leafhopper (Empoasca sp.). Natural enemies were: minute pirate bug (Orius tristicolor), parasitic wasps (Hymenoptera), and rove beetles (Staphylinidae). Over the 24 weeks of the experiment, LED-YC traps captured more dark-winged fungus gnats, sweet potato whiteflies, leafhoppers, and rove beetles compared with YC traps. Capture of western flower thrips, minute pirate bugs, and parasitic wasps were not significantly increased on the YC traps equipped with LEDs. The results indicate that the LED-YC traps attract three major pest insects in poinsettia greenhouses and do not catch more beneficial, minute pirate bugs and parasitic wasps, but may catch significant number of rove beetles. The results suggest that LED-YC traps may be useful to monitor and reduce pest populations in greenhouses.

Full access

Euonymus alatus (Thunb.) Sieb., commonly known as “burning bush,” is an extremely popular landscape plant in the United States as a result of its brilliant showy red leaves in fall. However, E. alatus is also seriously invasive because of its prolific seed production and effective seed dispersal by birds. Thus, development of sterile, non-invasive, seedless triploid E. alatus is in high demand. In this article, we report successful production of triploid E. alatus using endosperm tissues as explants. In our study, ≈50% of immature endosperm explants and 14% of mature endosperm explants formed compact, green calli after culture in the dark for 8 weeks and then under light for 4 weeks on Murashige and Skoog (MS) medium supplemented with 2.2 μM BA and 2.7 μM α-naphthaleneacetic acid (NAA). Approximately 5.6% of the immature endosperm-derived calli and 13.4% of mature endosperm-derived calli initiated shoots within 8 weeks after they were cultured on MS medium with 4.4 μM benzyladenine (BA) and 0.5 μM indole-3-butyric acid (IBA). Eighty-five percent of shoots rooted after culture on woody plant medium (WPM) containing 4.9 μM IBA for 2 weeks and then on hormone-free WPM medium containing 2.0 g·L−1 activated charcoal for 4 weeks. Eight independently regenerated triploid plants have been identified. Triploid plant regeneration rates observed were 0.42% from immature endosperm explants and 0.34% from mature endosperm explants, respectively, based on the number of endosperm explants cultured. Because triploid plants cannot produce viable seeds, and thus are sterile and non-invasive, some triploid E. alatus plant lines reported here can be used to replace the currently used invasive counterparts. Chemical names used: benzyladenine (BA), indole-3-butyric acid (IBA), and α-naphthaleneacetic acid (NAA).

Free access

Ferric chelate reductase (FRO) is a critical enzyme for iron absorption in strategy I plants, reducing Fe3+ to Fe2+. To identify FRO family genes in the local Citrus junos cultivar Ziyang Xiangcheng and to reveal their expression model, the citrus (Citrus sp.) genome was searched for homologies of the published sequence CjFRO1. Five FROs were found, including CjFRO1; these were named CjFRO2, CjFRO3, CjFRO4, and CjFRO5, respectively, and cloned via reverse transcription polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE) PCR. The deduced amino acid sequences of five CjFROs contained flavin adenine dinucleotide (FAD)-binding motifs, nicotinamide adenine dinucleotide (NAD)-binding motifs, and 6–10 transmembrane domains, with isoelectric points between 6.73 and 9.46, and molecular weights between 67.2 and 79.9 kD. CjFRO1 and CjFRO2 were predominantly found in the aboveground parts of C. junos, with CjFRO1 highly expressed in leaves, and CjFRO2 largely expressed in stems and leaves. CjFRO3 was less expressed in roots, stems, and leaves. CjFRO4 and CjFRO5 were predominately found in roots. Under iron-deficient conditions, CjFRO4 was significantly and specifically increased in the roots of C. junos, whereas CjFRO1 was upregulated in the roots and leaves.

Free access